Coaxial connector



y 1968 E. w. FORNEY, JR, ET AL 3,384,703

coAxIAL CONNECTOR 3 Sheets-Sheet 1 Filed May 26, 1964 IN VEN TOR.

EDGAR WILMQT F'aRNs7,'-TR. Rm-mm: SHURE Hocvsuueaun l l lgp l.

May 21, 1968 E. w. FORNEY, JR.. ET AL COAXIAL CONNECTOR 3 Sheets-Sheet 2Filed May 26, 1964 INVENTOR. EDGAR \A/ILMOI" Fonusy, In. "RKHARD SHUREHQGENmoBLER BY & n; w y i z United States Patent 3,384,703 COAXIALCONNECTOR Edgar Wilmot Forney, Jr., Harrisburg, and Richard ShureHogendobler, Camp Hill, Pa., assignors to AME Incorporated, Harrisburg,Pa. Filed May 26, 1964, Ser. No. 370,204 6 Claims. (Cl. 174-75) Thisinvention is directed to a coaxial connector which is crimpable tocoaxial cable of the type used for communication channels, such as,distributing closed circuit television signals.

The specialized cable developed for transmission of communicationsignals of higher frequencies generally includes a center conductorsurrounded and supported by a dielectric material, such as, foamedTeflon or polyethylene, in turn, supported by a relatively heavy tube ofconductive metal forming the cable outer conductor, the tube itselfbeing surrounded by a tough, thick, plastic sheath. This relativelyheavy cable construction is necessitated by the mode of energy transferwhich becomes very lossy if the cable dimensions are varied from thecable specification, as, for example, when the cable is slightlydeformed such that the outer conductor is more closely spaced to thecenter conductor than in other regions. This would occur in a bend ofthe cable if it were of a lighter construction.

On the other hand, the heavy construction makes such cable particularlydifiicult to terminate with standard connector constructions. The usualdilemma is that if the termination meets the electrical requirements bymaintaining a proper spacing throughout the connection then it is notsufficiently strong mechanically to withstand the loads to which thecable subjected, or if the cable is made sufficient mechanically, it haselectrical shortcomings. As a further problem, the relatively heavyconstruction of the cable in conjunction with its being filled with asolid dielectric such as foamed polyethylene or Teflon, makes the usualassembly procedures more tedious and requiring of the use of skilledlabor than with other and simpler cable constructions.

Accordingly, it is an object of the present invention to provide aconnector for coaxial cable of the type having a solid foamed dielectricmaterial surrounded by a relatively heavy metal tubing which provides anelectrical and mechanical termination of characteristics equal toapproaching the characteristics in the cable itself.

It is a further object to provide a coaxial connector construction whichis rapidly installable on semi-rigid coaxial cable.

It is yet another object to provide a novel coaxial connector sleeve andferrule assembly for use with coaxial cable.

It is an object to provide a connector sleeve construction and method ofassembly to coaxial cable which minimizes disturbance to cabledielectric and electrical discontinuity.

Other objects and attainments of the present invention will becomeapparent to those skilled in the art upon a reading of the followingdetailed description when taken in conjunction with the drawings inwhich there are shown and described illustrative embodiments of theinvention; it is to be understood, however, that these embodiments arenot intended to be exhaustive nor limiting of the invention, but aregiven for purposes of illustration in order that others skilled in theart may fully understand the invention and the principles thereof andthe manner of applying it in practical use so that they may modify it invarious forms, each as may be best suited to the conditions of aparticular use.

In the drawings:

FIGURE 1 is a perspective showing the connector of the inventioninstalled on a coaxial cable and crimped thereto;

FIGURE 2 is a section of the coaxial connector of the invention showingthe center pin member crimped to the center conductor of coaxial cable;

FIGURE 3 is a perspective of the connector crimping sleeve extension ofthe invention;

FIGURES 4 and 5 are perspective showing an end of the coaxial cablebefore and after stripping procedures, respectively;

FIGURES 6 and 7 are sectional views showing the insertion procedures forinserting the sleeve extension of the connector of the invention withina cable;

FIGURE 8 is a sectional view showing the sleeve extension of theconnector of the invention inserted and crimped to the cable by aferrule member in conjunction with details of a novel O-ring assemblywhich is part of the invention; and

FIGURE 9 is a perspective of the novel O-ring outer sleeve.

Referring now to FIGURE 1, a coaxial connector 10 is shown terminating acoaxial cable 12, the joint being formed by the connector ferrule andits engagement through crimping as at the crimp C to the cable outerconductor.

The forward end of 10 is adapted to make this a complementary end for aconnector half not shown which may be joined in an identical fashion toa further cable such as 12 or secured to some equipment to which thecable shown in FIGURE 1 is to be terminated.

The cable construction is shown in FIGURES 4 and 5 to include arelatively thick outer covering of dense plastic-like material 14,surrounding an outer conductor 16, which is a metal tubing, such as,aluminum or copper filled with a solid foam polyethylene dielectricmaterial 18. The dielectric material 18 supports a center conductor 20,which is typically solid copper rod. In accordance with the presentinvention, the cable is first severed with a transverse cut being madeas in FIGURE 4 and then stripped to expose a length of the centerconductor 20 and a length of the outer conductor 16, such lengths :beingrelated to the design of the connector shown in FIGURES 2 and 6 wherebythe portions fit within and over, respectively, portions of theconnector.

The connector 10 includes a central body member 32 having a rear sleeveextension 34 which is adapted to serve as a back-up member againstcrimping pressures and as a means to which the outer conductor 16 isterminated to .form the outer transmission path of the connection. Thesleeve 34 extends for a considerable length, preferably a length greaterthan the diameter of cable, the outer conductor 16 and includes at itsrear end a sharpened edge 36 having an internal bevel 38 disposed at anangle A with respect to the surface of 34 around the periphery of theextension. This angle A is held to a relatively small value to define asharp cutting edge at the rear of the extension for purposes to bedescribed hereinafter. The extension 34 is held to be of a thicknesswhich is just enough to resist being deformed during the crimpingoperation and is, in terms of the thickness of the outer conductor,preferably thinner than such and in any event as thin as possible,considering its function in linking the cable to the conductorelectrically and mechanically. Disposed about the surface of 34 are aseries of V-shaped indentations 40 which serve to break up the oxidationdeposits which may exist on the inner surface of the outer conductor 16of the cable so that a good electrical connection is assured between theconductor 16 and the extension 34. At the point where the outsidesurface of extension 34 joins the main body of 32 is a gasket 35 ofresilient and elastic material preferably of a size wherein, whenslipped over the extension, it will remain in position to avoid therequirement for separate loose pieces during shipment and prior to use.

Extending along the interior of 34 is a bore shown as 42, which isapproximately equal to the inner diameter of the outer conductor 16,less twice the thickness of the material of 34. Bore 42 flares outwardlywithin the body of 32 to define a bore 44 and then continues againforwardly of that into a bore 46 and to a bore 50. Between the bores 44and 46 is defined a step and face 48 and between the bores 50 and 46 isdefined a step and face 51. The bore 44 is somewhat larger than theinner diameter of the outer conductor 16 to compensate for the largerdiameter of the inner conductor formed by a portion of the central pinmember. This is to reduce electrical discontinuities. The spacingbetween the inner surface of 44 and the outer surface of portions of thecentral pin may he arrived at by standard procedures wherein thecharacteristic impedance of the section extending along 44 is adusted toapproximate the characteristic impedance of the cable. Fitted withinbore 46 is a dielectric plug shown as 52, which is seated against 48.The plug 52 includes a central bore housing and supporting the connectorcentral pin member, The bore 50 accommodates a forward spring shell '56which is flanged as at 54 and secured within 50 against the face 51 tolock the plug 52 against relative forward movement. The inner face of 52is positioned relative to the body 32 such that with the pin member 70secured to the center conductor 20 the cable may be worked forwardlyuntil 70 is stopped by 52 to thus position the connector duringassembly. The member 56 is relieved along its surface in an axial senseto define in dividual spring members which cooperate with complementaryportions on the half not shown. Sleeve extension 34 is housed within ametallic sleeve 39 which is formed inwardly as at 41 to lock 34 withinthe connector assembly. At the opposite end of 39 there is an annularrecess shown as 45 and a ring 64 which extends outwardly into a groove62 of a forward member 60 internally threaded as at 66 to cooperate withthe complementary jack or receptacle member for the connector. Member 39is, thus, locked to 60 and to 34 to form a structurally integralassembly.

The central pin member 70 includes a sleeve portion 72 adapted toreceive the end of the center conductor 20 and be crimped as at Cthereto. The sleeve 72 is joined to a reduced portion 74 which, in turn,is beveled as at 76 to assist in the mating operation with acomplementary connector half. The cooperation between '70 and plug 52 toresist or limit the forward axial movement of the pin relative to theconnector assembly is important for reasons which will be coveredhereinafter relative to assembly of the device on the cable.

FIGURE 3 depicts the general configuration of extension 34. The use of amember of this configuration has been found to be helpful in covering arelatively wide range of components with this same member. With themember 34, a given cable may be terminated to forward portions which arelarger or smaller to connect with larger or smaller cables, the portion39 being of a proper diameter.

Turning now to the assembly and method which is permitted by the aboveconstruction, FIGURES 4 and show the preferred preparation of the cableto the point shown in FIGURE 5 with a portion of the center conductorextending forwardly and a portion of the outer conductor 16 extendedforwardly and free of the outer protective sheath 14. As a next step thecentral pin member 70 is fitted onto 20 and crimped thereto, Thereafter,

with the ferrule member 80 placed over 34, the outer conductor 16 of thecable, the connector is held with the cable secured positioned in themanner shown in FIGURE 5 and with the beveled portion and cutting edgedefined by 38 being inserted just inside the outer conductor 16 of thecable. With the connector and cable so positioned, the connector is thenforced inwardly with a turning motion applied therto such that thecutting edge 38 bites into the dielectric material, forcing thedielectric down within bore 42 and breaking its cleavage to the innersurface of 16 without causing spaces or voids, Continued force appliedto the connector along with a slight rotation or twisting thereof willwork the extension 34 down to the position shown in FIGURE 7 and thencompletely within, in a position shown in FIGURE 8, with the conductor16 abutting against the gasket 35. With practice, this procedure takesonly a few seconds, the thinness of 34 in conjunction with the knifeedge and acting to facilitate the insertion by forcing the dielectricdownward into and along 42. Thereafter, a crimp may be applied to theferrule member 80 as indicated by numeral C in FIGURE 8. The crimp C ispreferably an O-type crimp applied in three spaced circumferential areasover the length of the extension 34, the inner crimp acting to compressand deform gasket 35 to seal the connector against the entry of gas,vapor or contaminannts at that point. The change in diameter of thetransmission path of the cable and connector effected by a thickness of34, will, of course, present a discontinuity but the thinness of 34 willtend to minimize this discontinuity and the connector has been found tobe quite satisfactory for uses in the lower ranges of so-called highfrequency communications, such as, about 225 megacycles. The presence ofthe continuous cable dielectric without voids extending from the cableup well into the connector is preferable to certain prior art approacheswherein the dielectric is cut off before entry into any portion of thecable. 7

Turning to yet a further aspect of the invention and to the ferrulemember 80, FIGURE 8 shows that at the rearward end thereof is included aradial flange extending outwardly shown as 82, which houses an O-ring orgasket of elastic material 90. In normal use, the gasket is selected ofdimensions such that it rests within 82 and has an inner diameterslightly smaller than the outer diameter of the outer conductor 16. Thisthen operates to seal the connection formed against the entry ofcontaminants through the outer end of the ferrule 80. The gasket 90 isheld in position by an outer member 84, which includes on its innersurface, a flange tapered inwardly as at 86 to facilitate its insertionover 82. The member 84 further includes an inwardly disposed flangeportion 88 which operates to lock and hold the gasket 90 within 82. Itis contemplated that the member 84 be made of a molded plastic-likematerial having elastic properties such that the member is readilydeformable so it may be snap-fitted over 80. As an additional point byhaving member 84 of an insulating material any problem which might occurby the use of copper, brass or the like, in connection with an aluminumouter conductor at an exposed point separated from 16 will becircumvented. Thus, the ferrule 80 will at its ends not be terminated tothe outer conductor 16 but will be spaced therefrom by the insulatingmaterial or gasket 35 and gasket 90. This would, of course, be the caseif 16 were of copper and 34 were of a different metal or differentlyplated.

In an actual embodiment manufactured in accordance with the inventionfor use with the cable wherein the outer conductor was of 0.375 inch indiameter and 0.325 inch in thickness, and the dielectric material 18 wasfoamed polyethylene, the member 34 was made of beryllium copper material0.014 inch in thickness and of an OD. equal to 0.319 inch. The cuttingedge or bevel 38 was made with an angle A equal to 30 degrees.

This unit was found to satisfactorily terminate 75 ohm cable at signalfrequencies of 10 to 216 megacycles.

Changes in construction will occur to those skilled in the art andvarious apparently different modifications and embodiments may be madewithout departing from the scope of the invention. The matter set forthin the foregoing description and accompanying drawings is offered by wayof illustration only. The actual scope of the invention is intended tobe defined in the following claims when viewed in their properperspective against the prior art.

What is claimed is: p

1. In a coaxial connection the combination including a coaxial cablehaving an inner conductor and an outer conductor coaxially disposedtherearound with the space between said inner and outer conductorssubstantially filled with a solid dielectric material, the said outerconductor being formed of a rigid metallic tubing of a given andconstant diameter along its length, a connector for said cable includingan outer metallic body having at one end means thereon to facilitatemating with another connector and having at the other end a sleeveextension, a bore extending through said body and a dielectric insertfitted within said bore toward the said one end, a center contact fittedwithin said insert terminated to the center conductor of said cable witha portion thereof projecting forwardly toward said one end for contactengagement with the center contact of another connector, a ferrulemember having an inner diameter approximately equal to the outerdiameter of said outer conductor and fitted thereover with the saidouter conductor positioned over said sleeve extension and the saidferrule member crimped inwardly terminating said outer conductor to saidsleeve extension and to said connector with said dielectric materialextending into said sleeve extension, the said sleeve extension having arelatively thin wall section and an outer diameter very slightly lessthan the said given inner diameter of the outer conductor and fittingtightly against the inner surface of the cable outer conductor andfurther having a sharp leading edge which separated the cable dielectricmaterial from the cable outer conductor without expansion of said outerconductor during insertion in said cable, whereby assembly of saidconnector to said cable is facilitated with minimum damage to thedielectric material, minimum change in spacing between the inner andouter conductive paths formed within said sleeve extension and minimumrequired force in inserting said sleeve extension into said cable outerconductor.

2. The connection of claim 1 wherein the said sharp leading edge of saidsleeve extension tapers inwardly from the end of said sleeve extensionto guide the said dielectric material of said cable within the bore ofsaid connector during insertion of said sleeve extension within saidcable outer conductor.

3. In a coaxial connection a connector comprised of first and secondouter metallic body members, each of said body members having a sleeveextension with a bore extending through the body member and each havingat one end portions for intermating, each of said first and second bodymembers including a dielectric insert in the bore at the one end witheach dielectric insert supporting coaxially within each said member acenter contact member, each center contact member including a portion atone end for intermating with the center contact member of the other bodymember, a coaxial cable terminated to each half, said cable including aninner conductor terminated to the center contact member and an outerconductor coaxially disposed therearound with the space between thecable inner and outer conductors being substantially filled with a soliddielectric material, the said outer conductor being formed of a rigidmetallic tubing of a given constant inner diameter and a given constantouter diameter and terminated to the said extension with the said boreof each of said body members receiving the inner conductor of said cableinserted therethrough and receiving a portion of the dielectric materialof said cable in unbroken length and in direct engagement with the innersurface of said sleeve extension, the said sleeve extension of each ofsaid body members further having at the end thereof opposite to the saidone end of said connector a sharp cutting edge of a maximum diameteronly slightly less than the said given inner diameter of said outerconductor, said edge being joined by an inwardly tapering portionoperable upon insertion of said extension into said cable in cleavingsaid dielectric material from the inner surface of said outer conductorand easing insertion of said extension within said cable with minimuminsertion force and minimum damage to said dielectric material and meansfitted over the said outer conductor of the cable in a positionoverlying the said sleeve extension of each of said body members toterminate the cable outer conductor to said sleeve extension for each ofsaid body members.

4. The connection of claim 3 including a ferrule of thin wall sectionand malleable metal for each of said body members, said ferrule havingan inner diameter before deformation only slightly larger than the outerdiameter of said outer conductor permitting a sliding fit thereover witheach said ferrule being crimped inwardly effecting the termination ofsaid outer conductor to the sleeve extension of each of said bodymembers.

5. In a coaxial connection, the combination comprising a coaxial cableincluding an inner conductor and an outer conductor of rigid metallictubing coaxially disposed therearound with the space therebetweensubstantially filled with a dielectric medium, a coaxial connectorcomprised of an outer metallic body having at the forward end means tomate with a further connector and having therein a bore extendingtherethrough and a dielectric insert secured within said bore, a centercontact member carried by said insert coaxially of said outer metallicsleeve and terminated to the inner conductor of said cable, the saidouter body including at the other end a metallic extension of thin wallsection inserted within said cable engaging the outer conductor thereof,a malleable ferrule positioned over said outer conductor and saidextension and crimped inwardly terminating said outer conductor to saidextension and to said connector, the said ferrule having at the endthereof opposite to the said one end of said connector an annular flangeextending out radially around said one end and then axially along saidouter conductor defining an annular recess between the inner surface ofsaid llange and the outer surface of said outer conductor, a gasketfitted within said space having an inner diameter less than the outerdiameter of said outer conductor and an outer diameter greater than theinner diameter of said flange in the axially extending portion thereofand compressed radially between the surfaces of said axially extendingportion and said outer conductor to seal said connector and said cableas terminated thereto through the outer conductor thereof, a gasketreceptacle of elastic material snapped over said flange and extendingaround the end of said ferrule, said receptacle including a portionextending radially inwardly to a diameter less than the average diameterof said gasket holding said gasket within said recess.

6. In a coaxial connection, the combination comprising a coaxial cableincluding an inner conductor and a rigid tubular outer conductorcomprised of a given metallic material, a connector including an outersleeve member having at one end means to interconnect to a matingconnector and at the other end a sleeve extension of an outer diameterand configuration fitted within the outer conductor of said cablewithout deforming said outer conductor, a bore extending along saidsleeve member and a dielectric insert fitted within said bore, saiddielectric insert carrying a center contact member terminated to theinner conductor of said cable, a ferrule member positioned over theouter conductor of said cable and over said sleeve extension and crimpedinwardly terminating said outer conductor to said sleeve extension andto said connector, the said ferrule member being of a metallic materialdifferent from the metallic material of said outer conductor,

the said ferrule member having the end thereof opposite References Citedto the said one end of said connector spaced outwardly UNITED STATESPATENTS in a radial sense away from and out of contact with the outerconductor of said cable and formed to define a 3,142,721 7/1964 f 174-89X recess extending therearound, a gasket of insulating ma- 5 3,245,0275/1966 zlegler 174 89 X terial compressed within said recess betweensaid ferrule FOREIGN PATENTS member and said outer conductor and aninsulating receptacle extending around the said end of said ferrule and942143 11/1963 Great Bntam' afiixed to said ferrule member, the saidinsulating recep- I tacle including a portion extending inwardlytrapping said 10 DARRELL CLAY Examine gasket within said recess. L. E.ASKIN, Examiner.

1. IN A COAXIAL CONNECTION THE COMBINATION INCLUDING A COAXIAL CABLEHAVING AN INNER CONDUCTOR AND AN OUTER CONDUCTOR COAXIALLY DISPOSEDTHEREAROUND WITH THE SPACE BETWEEN SAID INNER AND OUTER CONDUCTORSSUBSTANTIALLY FILLED WITH A SOLID DIELECTRIC MATERIAL, THE SAID OUTERCONDUCTOR BEING FORMED OF A RIGID METALLIC TUBING OF A GIVEN ANDCONSTANT DIAMETER ALONG ITS LENGTH, A CONNECTOR FOR SAID CABLE INCLUDINGAN OUTER METALLIC BODY HAVING AT ONE END MEANS THEREON TO FACILITATEMATING WITH ANOTHER CONNECTOR AND HAVING AT THE OTHER END A SLEEVEEXTENSION A BORE EXTENDING THROUGH SAID BODY AND A DIELECTRIC INSERTFITTED WITHIN SAID BORE TOWARD THE SAID ONE END, A CENTER CONTACT FITTEDWITHIN SAID INSERT TERMINATED TO THE CENTER CONDUCTOR OF SAID CABLE WITHA PORTION THEREOF PROJECTING FORWARDLY TOWARD SAID ONE END FOR CONTACTENGAGEMENT WITH THE CENTER CONTACT OF ANOTHER CONNECTOR, A FERRULEMEMBER HAVING AN INNER DIAMETER APPROXIMATELY EQUAL TO THE OUTERDIAMETER OF SAID OUTER CONDUCTOR AND FITTED THEREOVER WITH THE SAIDOUTER CONDUCTOR POSITIONED OVER SAID SLEEVE EXTENSION AND THE SAIDFERRULE MEMBER CRIMPED INWARDLY TERMINATING SAID OUTER CONDUCTOR TO SAIDSLEEVE EXTENSION AND TO SAID CONNECTOR WITH SAID DIELECTRIC MATERIALEXTENDING INTO SAID SLEEVE EXTENSION, THE SAID SLEEVE EXTENSION HAVING ARELATIVELY THIN WALL SECTION AND AN OUTER DIAMETER VERY SLIGHTLY LESSTHAN THE SAID GIVEN INNER DIAMETER OF THE OUTER CONDUCTOR AND FITTINGTIGHTLY AGAINST THE INNER SURFACE OF THE CABLE OUTER CONDUCTOR ANDFURTHER HAVING A SHARP LEADING EDGE WHICH SEPARATED THE CABLE DIELECTRICMATERIAL FROM THE CABLE OUTER CONDUCTOR WITHOUT EXPANSION OF SAID OUTERCONDUCTOR DURING INSERTION IN SAID CABLE, WHEREBY ASSEMBLY OF SAIDCONNECTOR TO SAID CABLE IS FACILITATED WITH MINIMUM DAMAGE TO THEDIELECTRIC MATERIAL, MINIMUM CHANGE IN SPACING BETWEEN THE INNER ANDOUTER CONDUCTIVE PATHS FORMED WITHIN SAID SLEEVE EXTENSION AND MINIMUMREQUIRED FORCE IN INSERTING SAID SLEEVE EXTENSION INTO SAID CABLE OUTERCONDUCTOR.